Self steering, three-axle bogie

ABSTRACT

The invention relates to a self-steering, three-axle bogie, in particular for a rail vehicle, comprising wheel sets ( 8, 9, 10 ) and wheel set bearing housings ( 2, 3, 4, 5, 6, 7 ) allocated to said sets. According to the invention, the outer wheel sets ( 8, 10 ) are counter-coupled and can be displaced in a longitudinal direction and the central wheel set ( 9 ) can be displaced in a transverse direction and is included in the control system. The wheel set bearing housings ( 2, 4, 6 ) on one side of the running gear and/or the wheel set bearing housings ( 3, 5, 7 ) on the other side of the running gear are coupled exclusively to the wheel set bearing housings ( 2, 3, 4, 5, 6, 7 ) lying on the same side and neighbouring wheel set bearing housings ( 2, 3, 4, 5, 6, 7 ) are coupled to a first rotary lever ( 14, 26 ) that is connected so that it can rotate to the corresponding wheel set bearing housing ( 4, 5 ) of the central wheel set ( 9 ), by means of a steering linkage-rotary lever configuration.

[0001] The invention relates to a self-steering three-axle bogie, inparticular for a rail vehicle, comprising wheel sets and associatedwheel set bearing housings, wherein the outer wheel sets arecounter-coupled and can be displaced in longitudinal direction, and thecentral wheel set can be displaced in transverse direction and isincluded in the control system, and wherein the wheel set bearinghousings on one side of the running gear and/or the wheel set bearinghousings on the other side of the running gear are coupled exclusivelyto the wheel set bearing housings lying on the same side of the runninggear.

[0002] The invention is particularly suited to application in railvehicles, in particular in locomotives. However, it is not limited tosuch applications.

[0003] A self-steering three-axle bogie for a rail vehicle is forexample known from DE 38 24 709 C2. This bogie is associated with adisadvantage in that the central wheel set is not included in thecontrol system, but instead, only the outer wheel set which is leadingin the direction of travel, and the outer wheel set which is trailing,are steered by way of corresponding steering linkages. As a result ofthis, the adaptability of the running gear to tighter radii of curvatureis severely limited, so that in tight curves disadvantageously hightracking forces are experienced.

[0004] In order to remedy this disadvantage it has been proposed toinclude the central wheel set in the control system too. For example, DE44 15 294 A1 discloses a corresponding self-steering three-axle bogiewith so-called steering beams by way of which the wheel bearing housingof the two sides of the running gear are coupled. This arrangement isassociated with a disadvantage in that, as a consequence of thetransverse connection between the sides of the running gear by way ofthe steering beam, design space is used, if need be even in the interiorof said running gear.

[0005] From DE 41 42 255 C2 a generic three-axle bogie is known. In thisarrangement the outer wheel sets are counter-coupled and arranged so asto be displaceable in longitudinal direction of the vehicle. The centralwheel set is displaceable in transverse direction, i.e. transversely tothe longitudinal direction, and is included in the control system. Thedisplaceability mentioned is ensured by conventional spring elements byway of which the wheel sets are attached to the running gear frame. Thisbogie overcomes the above-mentioned disadvantage, in that the wheel setbearing housings are now only coupled on the respective side of therunning gear, and in that—apart from the (internal) connection by way ofthe respective wheel sets—in the sense of the present description thereis no longer any (external) coupling between the wheel set bearinghousings of the two sides of the running gear. Coupling betweenneighbouring wheel set bearing housings is by way of a rotary lever.While this configuration saves a considerable amount of design space, itis however associated with the following disadvantages. While inclusionof the central wheel set in the control system makes it possible toachieve adaptation to almost any track curvature, depending on saidtrack curvature there is nonetheless a more or less considerablestriking angle between the wheel flange of the respective outer wheelset and the outer rail, which striking angle increases wear and tear andhas thus a negative effect on the service life of the wheel set.

[0006] U.S. Pat. No. 4,679,507 describes a further generic three-axlebogie for rail vehicles in which steering rods and angular levers arecoupled to the wheel set bearing housing of the central wheel set.Coupling of the wheel set bearing housings among themselves is by way ofrotary levers and steering linkages, with rotary levers impacting on thewheel set bearing housing of the central wheel set with a certainclearance by way of resilient pads. In this arrangement, the centralwheel set is guided by way of special steering rods transversely to thelongitudinal direction or direction of travel. This arrangement isassociated with a disadvantage in that it necessitates at least twodifferent points of connection at the wheel set bearing housing, so thatthis solution is relatively expensive to implement.

[0007] It is thus the object of the present invention to disclose ageneric bogie which does not have the described disadvantages of thestate of the art, or at least has them to a lesser extent, and inparticular which ensures good reduction of the striking angle whilebeing of simple design.

[0008] This object is met, starting with a self-steering three-axlebogie according to the preamble of claim 1, by the characteristicsdisclosed in the characterising part of claim 1.

[0009] The present invention is based on the technical teachingaccording to which a generic bogie which is of simple design and ensuresa good reduction in the striking angle can be obtained if neighbouringwheel set bearing housings are coupled, by way of asteering-linkage/rotary lever configuration, to a first rotary leverwhich is connected, so that it can rotate, to the associated wheel setbearing housing of the central wheel set.

[0010] Compared to the arrangement known from DE 41 42 255 C2, thiscombination of steering linkages and rotary levers provides thearrangement according to the invention with an additional degree offreedom in the plane which is arranged parallel to the track plane.While in the known arrangement the angle position of the respectiveouter wheel set in relation to the rail, i.e. the striking angle, at aparticular curvature of the track is defined by the angular levers andis invariable, in the solution according to the invention, thanks tothis additional degree of freedom, the respective outer wheel set canessentially adjust radially as a result of the predominant strikingforces at the outer rail. Consequently, the striking angle isconsiderably reduced. As a rule, a reduction essentially to zero ispossible, which advantageously leads to a clear reduction in the wearand tear of the wheel sets.

[0011] The configuration according to the invention, with the firstrotary lever which is connected, so that it can rotate, to theassociated wheel set bearing housing of the central wheel set, has theadditional advantage in that this is a very simple and space-savingarrangement which in addition also meets the function of a guide, inparticular of a transverse guide for the central wheel set. Thus,advantageously, such a guide requires no additional functionalcomponents—such as corresponding steering rods as they are known fromU.S. Pat. No. 4,679,507.

[0012] The steering-linkage/rotary lever configuration is preferablydesigned and arranged such that a striking angle of less than 10°results between the, in relation to the track, curve, outer wheel of theouter wheel set and the outer rail of the track curve. This can beachieved by a corresponding selection of the length of the steering androtary levers as well as the arrangement of the coupling points orfulcrums. Preferably, the striking angle is less than 5°. Furtherpreferably, the striking angle resulting in curves is essentially 0° sothat wear of the wheel flange at the outer wheel is reduced to aminimum.

[0013] The coupling of wheel set bearing housings can take place eitheron one side or on both sides, i.e. either on one side of the runninggear or on both sides of the running gear. Advantageous variants of thebogie according to the invention provide for the couplings of the wheelset bearing housings of one side of the running gear to be provided in asymmetrical manner as they are provided for the wheel set bearinghousings of the other side of the running gear, said symmetry being inrelation to the longitudinal axis of the rail vehicle. In this way,particularly favourable steering behaviour is achieved, irrespective ofthe orientation of the track curve being driven on, with even wear andtear of the wheels of the respective wheel set being achieved.

[0014] Preferred variants of the bogie according to the invention—atleast in the neutral position on a straight track—provide for a firststeering linkage, arranged transversely in relation to the longitudinaldirection, between a first joint on the first rotary lever and a secondjoint on the wheel set bearing housing of a first outer wheel set. Theinclined position of the first steering linkage, as a result of theensuing motion component directed towards the inside of the track curve,advantageously favours radial alignment of the outer wheel set inrelation to the track curve, and thus a reduction in the striking angle.

[0015] Steering behaviour which is particularly favourable in relationto a reduction in the striking angle results in configurations which onboth sides provide a first steering linkage which is correspondinglypositioned at an incline.

[0016] Basically, the first rotary lever can be designed as desired.Preferably, it is an angular lever comprising a first arm and a secondarm as well as a fulcrum pin which is fixed to the frame, as thisprovides a configuration which is particularly simple in design.

[0017] In this arrangement, in its neutral position, the first arm ispreferably aligned transversely in relation to the longitudinal axis ofthe vehicle, particularly preferably perpendicularly, in order toachieve correspondingly large control movements, depending on thetransverse displacement of the central wheel set, which controlmovements make possible optimal adaptation to a wide range of trackcurvatures.

[0018] The first rotary lever may be connected to any point of theassociated wheel set housing of the central wheel set by way of a thirdjoint arranged on said rotary lever's second arm. Preferably, the firstrotary lever is connected to the face of the wheel set bearing of thecentral wheel set by way of a third joint which is arranged on saidrotary lever's second arm. This results in an arrangement which isparticularly easy to produce and to service.

[0019] Incidentally, particularly favourable motion transfer is achievedif the fulcrum of the first rotary lever and the coupling point of thefirst rotary lever to the wheel set bearing of the central wheel set arepositioned on a line which in the neutral position is essentiallyparallel in relation to the longitudinal direction of the vehicle. Tothis effect, the second arm of the first rotary lever, which firstrotary lever is an angular lever, can for example in its neutralposition essentially be aligned in longitudinal direction of thevehicle.

[0020] Preferred variants (preferred because they are of particularlysimple design) of the bogie according to the invention provide for asecond rotary lever with a fulcrum pin which is fixed to the frame, saidsecond rotary lever being associated with the wheel set bearing housingof a second outer wheel set. In this arrangement, a second steeringlinkage which leads to the wheel set bearing housing of the second outerwheel set is coupled to a fourth joint of the second rotary lever. Afifth joint of the second rotary lever, which fifth joint in the neutralposition is arranged beyond the fulcrum pin in relation to thelongitudinal direction of the vehicle, is connected to a third steeringlinkage which leads to a joint on the first rotary lever. Thisconfiguration with the second rotary lever achieves in a simple waycounter-coupling of the first and second outer wheel set.

[0021] In this arrangement, the second rotary lever can be of anydesign. Preferably, it is a simple straight lever.

[0022] The position of the fulcrum pin of the second rotary leverbetween the fourth and the fifth joint can be selected depending on thedesired or required motion transfer between the wheel set bearinghousing of the central wheel set or the first rotary lever and the wheelset bearing housing of the second outer wheel set. In preferred variantsthe fulcrum pin of the second rotary lever is centred.

[0023] The third steering linkage can be coupled in any desired way tothe first rotary lever. Preferably, the third steering linkage leads tothe region of the first joint on the first rotary lever in order toachieve particularly favourable motion transfer. Preferably, the thirdsteering linkage leads to the first joint on the first rotary lever inorder to achieve a particularly simple design, since in this case onlyone joint is required at that position for coupling the first steeringlinkage and the third steering linkage.

[0024] There are further advantages of the invention in that noadditional design space is used in the interior of the running gear, andthat at the same time the central wheel set is also included in thecontrol system so that all three wheel sets are used for steering incurves. There is a further advantage in that only existing points ofconnection are used on the wheel set bearing housings, and onlyrelatively few components are required.

[0025] As a result of active inclusion of the central wheel set in thecontrol system the horizontal spring excursion forces of the wheel setsprings, which forces oppose the control motion, can be overcome moreeasily, and in particular in curves with tighter radii in which largerhorizontal excursions of the wheel set springs are required, thealignment of the wheel set shaft in relation to the centre of the curveis improved.

[0026] Advantageous embodiments and improvements of the invention resultfrom the dependent claims or the following description of a preferredembodiment which refers to the enclosed drawing. The following is shown:

[0027]FIG. 1 a diagrammatic representation of the running gear of apreferred embodiment of the self-steering three-axle bogie according tothe invention.

[0028]FIG. 1 shows the running gear 1 of a three-axle bogie, accordingto the invention, for a rail vehicle. The running gear comprises arunning gear frame (not shown in FIG. 1) which comprises longitudinaland transverse beams.

[0029] The wheel set bearing housings 2 to 7 of the three wheel sets 8,9, 10 are attached to the longitudinal beams by way of spring elements(not shown), namely wheel set bearing housings 2, 3 for the first wheelset 8, which hereinafter is referred to as the first outer wheel set;wheel set bearing housings 4, 5 for the second wheel set 9, whichhereinafter is referred to as the central wheel set; and wheel setbearing housings 6, 7 for the third wheel set 10, which hereinafter isreferred to as the second outer wheel set. The wheel sets 8, 9, 10comprise wheels 11. The wheel sets 8, 9, 10 may be driven by drivemotors (not shown), for example axle suspension motors or motors mountedon the bogie frame.

[0030] The wheel set bearing housings 2, 3, 6, 7 of the two outer wheelsets 8, 10, inter alia can be displaced in the direction of travel oropposite to the direction of travel of the rail vehicle, as indicated bydirectional arrows x1, x2. The wheel set bearing housings 4, 5 of thecentral wheel set 9, inter alia can be displaced perpendicularly to thedirection of travel of the rail vehicle, as indicated by directionalarrows y1, y2.

[0031] The wheel set bearing housings 2, 3, 4, 5, 6, 7 are only coupledon the same side of the running gear by way of steering-linkage/rotarylever configurations.

[0032] A first steering linkage 12, which in the neutral position asshown in FIG. 1 is arranged transversely to the longitudinal directionof the vehicle, is arranged between a first joint 13 of a first rotarylever, in the form of an angular lever 14, and a second joint 15 on thewheel set bearing housing 3 of the first outer wheel set 8.

[0033] The angular lever 14 comprises a first arm 14.1 and a second arm14.2, with said arms in the embodiment shown being of approximately thesame length. However, depending on the desired motion transfer, saidarms may also be of different length in other variants.

[0034] In the neutral position shown, the first arm 14.1 is alignedessentially perpendicularly in relation to the longitudinal direction ofthe vehicle, while the second arm 14.2, in this position is alignedessentially parallel in relation to the longitudinal direction of thevehicle.

[0035] The angular lever 14 comprises a fulcrum pin 16 which is fixed tothe frame, and on the end of its second arm 14.2 is connected to theface of the wheel set bearing 5 of the central wheel set 9, by way ofthe third joint 17.

[0036] A second rotary lever 18 comprising a centred fulcrum pin 19which is fixed to the frame is associated with the wheel set bearinghousing 7 of the second outer wheel set 10; wherein the secondsteering-linkage 20, which leads to the wheel set bearing housing 7 ofthe second outer wheel set 10, is connected to the fourth joint 21 ofthis second rotary lever 18; and wherein the fifth joint 22 of thissecond rotary lever 18 is connected to a third steering linkage 23 whichin turn leads to the already mentioned first joint 13 of the angularlever 14.

[0037] In the embodiment shown, the couplings of the wheel set bearinghousings 3, 5, 7 of one side of the running gear are built so as to besymmetrically realised, in relation to the longitudinal axis of the railvehicle, also on the wheel set bearing housings 2, 4, 6 of the otherside of the running gear.

[0038] A first steering linkage 24, arranged at an inclination, isarranged between a first joint 25 of a first rotary lever in the form ofan angular lever 26 and a second joint 27 of the wheel set bearinghousing 2.

[0039] The angular lever 26 comprises a fulcrum pin 28 which is fixed tothe frame and is connected to the front of the wheel set bearing 4 ofthe central wheel 9 set by way of the third joint 29 of the second armof said angular lever 26.

[0040] A second rotary lever 30 with a centered fulcrum pin 31 which isfixed to the frame is associated with the wheel set bearing housing 6 ofthe second outer wheel set 10; wherein the second steering linkage 32,which leads to the wheel set bearing housing 6, is connected to thefourth joint 33 of said second rotary lever 30; and wherein the fifthjoint 34 of said second rotary lever 30 is connected to a third steeringlinkage 35 which on the other end leads to the already mentioned firstjoint 25 of the angular lever 26.

[0041] Below, the function of the self-steering three-axle bogie 1 isdescribed.

[0042] By coupling the wheel set bearing housing 3 of the first outerwheel set 8 to the wheel set bearing housing 5 of the central wheel set9 by way of the first steering linkage 12 and the angular lever 14, andcoupling the wheel set bearing housing 7 of the second outer wheel set10 to the wheel set bearing housing 5 of the central wheel set 9 by wayof the second steering linkage 20, the second rotary lever 18, the thirdsteering linkage 23 and the angular lever 14, as well as by thesymmetrical arrangement on the opposite side of the running gear, inconjunction with the wheel set bearing housings 2, 3, 6, 7 (which can bedisplaced in the direction of travel (x1) or opposite the direction oftravel (x2) of the rail vehicle) of the outer wheel sets 8, 10, and thewheel set bearing housings 4, 5 (which can be displaced in perpendiculardirection of travel (y1, y2) of the rail vehicle) of the central wheelset 9, a counter coupling of the outer wheel sets 8, 10 results when thevehicle travels in a curve.

[0043] In this arrangement, counter-coupling of the first and secondouter wheel sets 8 and 10 is simply effected by designing the secondrotary lever 18, 30 with the fourth joint 21, 33 and the fifth joint 22,34 which in the neutral position is arranged beyond the fulcrum pin 19,31 in relation to the longitudinal direction of the vehicle.

[0044] For example, if the wheel set bearing housing 2 of the firstouter wheel set 8 is displaced in the direction x2, then the wheel setbearing housing 6 of the second outer wheel set 10 is constrained todisplacement in the direction x1, while the wheel set bearing housing 4of the central wheel set 9 is constrained to displacement in thedirection y1. At the same time, the wheel set bearing housing 3 of thefirst outer wheel set 8 is displaced in the direction x2, the wheel setbearing housing 7 of the second outer wheel set 10 is displaced in thedirection x2 and the wheel set bearing housing 5 of the central wheelset 9 is displaced in the direction y1.

[0045] In this arrangement, inclination of the first steering-linkages12 and 24, due to the resulting motion component which is directedtowards the inside of the track curve, favours an alignment of the firstouter wheel set 8 which alignment is radial in relation to the trackcurve, and thus favours a reduction in the striking angle between theouter wheel of the outer wheel set 8 and the outer rail of the trackcurve.

[0046] The components of the arrangement—in particular the rotary levers14, 18 as well as 26, 30, the steering linkages 12, 20, 23 as well as24, 32, 35 and their joints as well as rotational axes—are arranged anddesigned such that in a wide range of radii of curvature of the trackthe first outer wheel set 8 and the second outer wheel set 10 are atleast to a considerable extent aligned radially in relation to thecurved track. In other words, a striking angle of less than 5° resultsbetween the outer wheels of the outer wheel sets 8, 10 and the outerrail of the curved track. In a wide range of radii of curvature, thisstriking angle is essentially 0°.

1. A self-steering three-axle bogie, in particular for a rail vehicle,comprising wheel sets (8, 9, 10) and wheel set bearing housings (2, 3,4, 5, 6, 7) allocated to said sets, wherein the outer wheel sets (8, 10)are counter-coupled and can be displaced in a longitudinal direction andthe central wheel set (9) can be displaced in a transverse direction andis included in the control system; and wherein the wheel set bearinghousings (2, 4, 6) on one side of the running gear and/or the wheel setbearing housings (3, 5, 7) on the other side of the running gear arecoupled exclusively to the wheel set bearing housings (2, 3, 4, 5, 6, 7)lying on the same side of the running gear, characterised in thatneighbouring wheel set bearing housings (2, 3, 4, 5, 6, 7) are coupled,by means of a steering-linkage/rotary lever configuration, to a firstrotary lever (14, 26) which is connected, so that it can rotate, to thecorresponding wheel set bearing housing (4, 5) of the central wheel set(9).
 2. The bogie according to claim 1, characterised in that thesteering-linkage/rotary lever configuration is designed and arrangedsuch that a striking angle of less than 10°, preferably of less than 5°,particularly preferably of essentially 0°, between the outer wheel ofthe respective outer wheel set and the outer rail of the track curveresults.
 3. The bogie according to claim 1 or 2, characterised in thatthe couplings of the wheel set bearing housings (2, 4, 6) of one side ofthe running gear are symmetrically realised, in relation to thelongitudinal axis of the rail vehicle, also in the wheel set bearinghousings (3, 5, 7) of the other side of the running gear.
 4. The bogieaccording to any one of the preceding claims, characterised in that afirst steering linkage (12, 24), arranged transversely in relation tothe longitudinal direction, is provided between a first joint (13, 25)on the first rotary lever (14, 26) and a second joint (15, 27) on thewheel set bearing housing (3, 2) of a first outer wheel set (8).
 5. Thebogie according to any one of the preceding claims, characterised inthat the first rotary lever is an angular lever (14, 26) comprising afirst arm and a second arm and a fulcrum pin (16, 28) which is fixed tothe frame.
 6. The bogie according to claim 5, characterised in that thefirst rotary lever is connected to the face of the wheel set bearing (5,4) of the central wheel set (9) by way of a third joint (17, 29) whichis arranged on the second arm of said first rotary lever.
 7. The bogieaccording to any one of the preceding claims, characterised in that asecond rotary lever (18, 30) with a fulcrum pin (19, 31) which is fixedto the frame is associated with the wheel set bearing housing (7, 6) ofthe second outer wheel set (10), wherein a second steering linkage (20,32) which leads to the wheel set bearing housing (7, 6) of the secondouter wheel set (10) is coupled to a fourth joint (21, 33) of the secondrotary lever (18, 30), and wherein a fifth joint (22, 34) of the secondrotary lever (18, 30), which fifth joint (22, 34) is arranged beyond thefulcrum pin (19, 31), is connected to a third steering linkage (23, 35)which leads to a joint (13, 25) on the first rotary lever (14, 26). 8.The bogie according to claim 7, characterised in that the fulcrum pin(19, 31) of the second rotary lever (18, 30) is centred.
 9. The bogieaccording to claim 7 or 8, characterised in that the third steeringlinkage (23, 35) leads to the first joint (13, 25) on the first rotarylever (14, 26).